Conventionally, there have been cases where a stent, which is formed in the shape of a hollow cylinder having a multiplicity of openings in its side wall from a metallic wire or the like, to be expanded in a lumen of a living body, such as a blood vessel, bile duct, trachea, esophagus and urethra, is used for improvement of a stenosed part or an obstructed part generated in the lumen of the living body.
In connection with the case of a self-expandable stent in which the stent itself has a self-expanding function, for example, there has been known a stent delivery system in which the stent is delivered into a lumen of a living body in the state of being compressed and contained in a gap between an inner tube and an outer tube, and then the outer tube is retracted proximally so as to release the stent, whereby the stent is put indwelling in a desired part in the lumen.
As disclosed in Japanese Application Publication No. 2007-504897, for example, the above-mentioned stent delivery system has an operating mechanism for moving the outer tube in an axial direction relative to the inner tube. In the operating mechanism, a gear rack is meshed with a gear of a rotatable wheel, and the outer tube is configured to be connected to an end portion of the gear rack. With the wheel rotated in a predetermined direction, the gear rack is advanced and retracted in the axial direction so as to move the outer tube relative to the inner tube, whereby the stent is released to the exterior of the outer tube.